In X-ray analyzers, i.e., X-ray diffractometers, fluorescent X-ray devices, small-angle X-ray scattering devices, and the like, X-rays generated from an X-ray generator irradiate a specimen targeted for analysis. In a typical X-ray generator, electrons generated from a cathode are made to collide against the surface of an anode, thereby generating X-rays from the surface of the anode. The region where the electrons collide, i.e., the region where X-rays are generated, is typically called the X-ray focal point.
The wavelength of the X-rays generated from the anode is determined by the material of the region that corresponds to the X-ray focal point in the anode. Known materials for anodes include Cu (copper), Mo (molybdenum), Cr (chromium), Co (cobalt), and the like. The material of the anode is selected, as appropriate, according to the type of analysis that is to be carried out. For example, in a case in which structural analysis of a protein is to be carried out by an X-ray diffractometer, a plurality of materials selected from the above plurality of materials would be employed.
According to Patent Literature 1, there is known an X-ray generator in which two types of X-ray generation zone are provided to a single anode, and one of two X-ray wavelengths is selectively generated as needed in a single X-ray generator by selectively disposing one of the zones in a position facing a cathode. In this X-ray generator, a mobile platform is caused to move by the rotation of a threaded shaft, whereby an anode supported by the mobile platform is caused to move relative to a cathode, and this relative motion causes one kind of X-ray zone among two to be selectively disposed in a position facing the cathode.
The device of Patent Literature 1 presents a problem in that parallel movement of the anode is caused by only one drive mechanism, which is disposed at a position separated from the center rotational axis of the anode, and therefore the anode oscillates laterally and tilts during the parallel movement, making for difficulty in correctly determining the position of the X-ray generation zone facing the cathode.
Furthermore, according to Patent Literature 2, there is known a configuration in which an anode housing supporting the anode is moved by negative pressure caused by air suction, and this movement causes one kind of X-ray zone among two on the anode to be selectively disposed in a position facing the cathode. However, in the device of Patent Literature 2, the negative pressure caused by air suction is applied to the anode at a position separated from the center rotational axis of the anode, and therefore the anode ends up oscillating laterally and tilting during parallel movement, making it difficult to correctly determine the position of the X-ray generation zone facing the cathode.
Also, according to Patent Literature 3, there is known a configuration in which a rotating anode provided with a plurality of X-ray generation zones is caused to move parallel to a cathode, whereby any one of the plurality of X-ray generation zones is caused to be disposed in a position facing the cathode. Moreover, in FIG. 5 of Patent literature 3 a technique for urging the anode in one direction using a spring is disclosed.
However, Patent Literature 3 does not indicate a specific configuration for causing parallel movement of the rotating anode. It follows that no explanation of a technique for preventing the anode from oscillating laterally or tilting during parallel movement is indicated.
Furthermore, according to Patent Literature 4, there is known a configuration in which a movable screw is caused to move, whereby a rotating anode provided with a plurality of X-ray generation zones is caused to move parallel to a cathode, which leads to any one of the plurality of X-ray generation zones being disposed in a position facing the cathode. Also, in FIG. 1 of Patent Literature 4, there is disclosed a technique for urging the anode via an elastic member such as a coil spring, in order to make it possible to move the movable screw with little force, offsetting the force with which the rotating anode is pushed toward art anode accommodating chamber at atmospheric pressure.
In the device of Patent Literature 4, the outer peripheral surface of the shaft portion of the rotating anode is made to function as a guiding surface and the rotating anode is caused to move in a parallel fashion. The shaft portion of the rotating anode functioning as a guiding surface is not the main point. Moreover, making the shaft portion of the rotating anode a highly precise guiding surface is extremely difficult from a processing perspective. Accordingly, the device of Patent Literature 4 presents the risk that the anode will oscillate laterally or tilt during parallel movement, causing difficulty in correctly determining the position of the X-ray generation zone facing the cathode.